 /*******************************************************************************
  * Copyright (c) 2002, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.cheatsheets.actions;

 import org.eclipse.jface.action.IAction;
 import org.eclipse.jface.viewers.ISelection;
 import org.eclipse.swt.events.*;
 import org.eclipse.swt.widgets.*;
 import org.eclipse.ui.*;
 import org.eclipse.ui.internal.cheatsheets.CheatSheetPlugin;

 /**
  * This is the action used to contribute the CheatSheets menu to the workbench's
  * help menu.
  */
 public class CheatSheetMenuAction implements IWorkbenchWindowPulldownDelegate2, IPropertyListener {
     /**
      * The menu created by this action
      */
     private Menu fMenu;

     /**
      * Indicates whether the cheat sheet history has changed and
      * the sub menu needs to be recreated.
      */
     protected boolean fRecreateMenu = false;

     /**
      * The constructor.
      */
     public CheatSheetMenuAction() {
         CheatSheetPlugin.getPlugin().getCheatSheetHistory().addListener(this);
     }

     /* (non-Javadoc)
      * @see IWorkbenchWindowActionDelegate#dispose
      */
     public void dispose() {
         setMenu(null);
         CheatSheetPlugin.getPlugin().getCheatSheetHistory().removeListener(this);
     }

     /**
      * Fills the drop-down menu with cheat sheets history
      *
      * @param menu the menu to fill
      */
     protected void fillMenu(Menu menu) {
         CheatSheetMenu cheatsheetMenuMenuItem = new CheatSheetMenu();
         cheatsheetMenuMenuItem.fill(menu, 0);
     }

     /* (non-Javadoc)
      * @see org.eclipse.ui.IWorkbenchWindowPulldownDelegate#getMenu(org.eclipse.swt.widgets.Control)
      */
     public Menu getMenu(Control parent) {
         return null;
     }

     /* (non-Javadoc)
      * @see org.eclipse.ui.IWorkbenchWindowPulldownDelegate2#getMenu(org.eclipse.swt.widgets.Menu)
      */
     public Menu getMenu(Menu parent) {
         setMenu(new Menu(parent));
         fillMenu(fMenu);
         initMenu();
         return fMenu;
     }

     /* (non-Javadoc)
      * @see IWorkbenchWindowActionDelegate#init
      */
     public void init(IWorkbenchWindow window) {
     }

     /**
      * Creates the menu for the action
      */
     private void initMenu() {
         // Add listener to repopulate the menu each time
 // it is shown because of dynamic history list
 fMenu.addMenuListener(new MenuAdapter() {
             public void menuShown(MenuEvent e) {
                 if (fRecreateMenu) {
                     Menu m = (Menu)e.widget;
                     MenuItem[] items = m.getItems();
                     for (int i=0; i < items.length; i++) {
                         items[i].dispose();
                     }
                     fillMenu(m);
                     fRecreateMenu= false;
                 }
             }
         });
     }
     
     /* (non-Javadoc)
      * @see org.eclipse.ui.IPropertyListener#propertyChanged(java.lang.Object, int)
      */
     public void propertyChanged(Object source, int propId) {
         fRecreateMenu = true;
     }

     /* (non-Javadoc)
      * @see IWorkbenchWindowActionDelegate#run
      */
     public void run(IAction action) {
     }

     /* (non-Javadoc)
      * @see IWorkbenchWindowActionDelegate#selectionChanged
      */
     public void selectionChanged(IAction action, ISelection selection) {
     }

     /**
      * Sets this action's drop-down menu, disposing the previous menu.
      *
      * @param menu the new menu
      */
     private void setMenu(Menu menu) {
         if (fMenu != null) {
             fMenu.dispose();
         }
         fMenu = menu;
     }
 }

